Morphology controllable synthesis of yttrium oxide-based phosphors from yttrium citrate precursors (original) (raw)
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SYNTHESIS OF NANO YTRRIUM OXIDE PHOSPHORS BY SIMPLE METHODS AND THEIR MORPHOLOGICAL STUDIES
iaeme
Among the family of rare earth compounds, yttrium oxide is a widely used material. Due to its chemical and physical properties, it is well known that yttrium oxide is a common luminescent host material. In many of the applications, reduction of the yttrium oxide crystallite size into the nanometer regime would result in improved performance compared to coarse grained yttrium oxide. This is particularly evident in phosphor application, where the phosphor efficiency varies inversely as the square of the particle size due to quantum confinement effect In this paper, synthesis and characterization of yttrium oxide by various methods are analyzed. Many research works is done on synthesis of Yttrium oxide and their characterization. Yttrium oxide samples are prepared by methods like Wet chemical, solvothermal process, and Sol-gel method. Then the samples are analyzed by XRD, SEM, EDAX and UV-Vis absorption studies. By optimizing various synthesis conditions, nanophosphors with high quantum efficiency and wide structural tenability can be prepared for their use in future display applications.
Micro & Nano Letters, 2012
In this study, Y 2 O 3 :Eu nanocrystals (NCs) were prepared through the combustion, Pechini and hydrothermal methods followed by the heat treatment of samples at 873 K. The resultant NCs were investigated by X-ray diffractometery, scanning electron microscopy, transmission electron microscopy, selected area electron diffractometery and photoluminescence (PL) spectroscopy. The obtained sample by the Pechini method presents cubic phase, whereas the hydrothermal sample consists of different phases (cubic, monoclinic and hexagonal phases of Y 2 O 3 besides yttrium nitrate hydrate phase). Cubic and monoclinic phases of Y 2 O 3 as well as tetragonal phase of yttrium oxide nitride (YO(NO 3 ) 3 ) phases were observed in combustion sample before heat treatment, whereas just the cubic phase stayed after heat treatment of this sample. The morphological investigations demonstrated that the hydrothermal sample has flower-like morphology with micron-size petals, whereas other samples have rounded particles. The PL intensity and chromaticity of Pechini sample are not as good as combustion and hydrothermal samples, but low agglomeration of the Pechini sample makes it good candidate for biological applications as a luminescence sensors and tags.
2011
Yttrium oxide doped with europium (Y2O3: Eu3+) is one of the main red emitting phosphor used in lightning industry and other optoelectronic devices [1-3]. To improve brightness and resolution of displays, it is important to develop phosphors with controlled morphology and small particle sizes. In order to achieve improved luminescent properties of Y2O3: Eu3+ the precursors characteristics as well as the synthetic route are very important factors.
Studies on Y2O3: Eu phosphor with different particle size prepared by wet chemical method
Journal of Alloys and Compounds 483 (2009) 346–349, 2008
Abstract: Europium activated yttrium oxide phosphorswere prepared by reagent simultaneous addition technique, using oxalic acid as precipitating reagent. The aim of the paper is to establish the flux influence and thermal regime on photoluminescence and morpho-structural characteristics of phosphor powders. In this respect different mineralising agents such as sodium/lithium carbonate, sodium tetraborate ans sodium pyrophosphatewere used during the thermal synthesis stage. Thermal analysis,X-ray diffraction, scanning electron microscopy, infrared spectroscopy and photoluminescence measurements were used to investigate precursor and phosphor powders. The correlation between the phosphor properties and precursor quality enabled us to select the optimal synthesis conditions.
Hydrothermal synthesis of nanostructured Y 2 O 3 and (Y 0.75 Gd 0.25) 2 O 3 based phosphors
Examples of (Y 2 O 3 -Gd 2 O 3 ):Eu 3+ and Y 2 O 3 :(Yb 3+ /Er 3+ ) rare earth oxide-based phosphors are presented to highlight the controlled synthesis of 1D and 2D nanostructures through simple hydrothermal method. Conversion of the starting nitrates mixture into carbonate hydrate phase is performed with the help of ammonium hydrogen carbonate solution during hydrothermal treatment at 200°C/3 h. Morphological architectures of rare earth oxides obtained after subsequent powders thermal treatment at 600 and 1100°C for 3 and 12 h and their correlation with the optical characteristics are discussed based on Xray powder diffractometry, field emission scanning electron microscopy, infrared spectroscopy and photoluminescence measurements. Strong red and green emission followed by the superior decay times are attributed to the high powders purity and homogeneous dopants distribution over the host lattice matrix.
Synthesis of Y 2 O 3 :Eu 3+ micro- and nanophosphors by sol-gel process
Journal of Physics: Conference Series, 2009
In this paper, optical properties of Y2O3:Eu 3+ micro-and nanophosphors synthesized by sol-gel process are reported. Citric acid and tartaric acid were employed as chelating agents. Different factors effecting structures and properties of the phosphors, such as concentration of Eu3+, sintered temperature and the ratio of metal ions to tartaric acid, were examined. Crystal structure of the particles was investigated by X-ray diffraction (XRD) technique. The results showed that the phosphor powders completely crystallized at 600°C. Morphology and particle size of the phosphors were studied by scanning electron microscope (SEM) and transmission electron microscope (TEM). The particle size of the obtained phosphors varied from 1 to 6 μm (using citric acid as chelating agent) and from 20 to 30 nm (using tartaric acid as chelating agent).
Open Chemistry, 2014
Yttrium silicate doped with cerium (Y2SiO5:Ce) was obtained from Y-Ce-Si based precursors prepared by the simultaneous addition of reagents (SimAdd) technique. The synthesis of the precursors was done in well controlled conditions using ammonium oxalate, ammonium carbonate or urea as precipitating agents. Results regarding the influence of precipitating agents on the morpho structural and photoluminescent characteristics of Y2SiO5:Ce are reported. The TG analysis in correlation with EGA, FT-IR and XRD investigations reveals the formation of oxalate, hydroxy-carbonate or hydroxy-nitrate based compounds, the same as the conversion of the precursors to well crystallized yttrium silicate. XRD patterns show that the precursors are amorphous except for the sample prepared with ammonium oxalate. Depending on the precipitation conditions, the phosphors phase composition varies from single phase (X2-Y2SiO5) to a mixture of phases (X2-Y2SiO5, X1-Y2SiO5, Y2O3). Under UV excitation, phosphors e...
Optical Materials, 2015
This work reports on the synthesis and characterization of Y 2 O 3 :Eu 3+ powders obtained by the hydrothermal method. We studied the influence of different pH values (7-12) and Eu 3+ concentrations (2.5-25 mol%) on the structural, morphological and luminescent characteristics of Y 2 O 3 :Eu 3+ powders. The hydrothermal synthesis was performed at 200°C for 12 h by employing Y 2 O 3, HNO 3 , H 2 O and Eu (NO 3) 3 as precursors, in order to obtain two sets of samples. The first set of powders was obtained with different pH values and named Eu5PHx (x = 7, 8, 9, 10, 11, and 12), and the second set was obtained by using a constant pH = 7 with different Eu concentrations, named EuxPH7 (x = 2.5, 5, 8, 15, 20 and 25). The XRD spectra showed that the Y 2 O 3 :Eu 3+ powders exhibited a cubic phase, regardless of the pH values and Eu 3+ concentrations. The SEM observations indicated that pH influenced the morphology and size of phosphors; for instance, for pH = 7, hexagonal microplatelets were obtained, and microrods at pH values from 8 to 12. Doping Y 2 O 3 with various Eu 3+ concentrations (in mol%) also produced changes in morphology, in these cases, hexagonal microplatelets were obtained in the range of 2.5-5 mol%, and non uniform plates were observed at higher doping concentrations ranging from 8 to 25 mol%. According to our results, the microplatelets synthesized with a pH of 7 and an 8 mol% Eu 3+ concentration presented the highest luminescence under excitation at 254 nm. All of these results indicate that our phosphors could be useful for applications of controlled drug delivery, photocatalysis and biolabeling.
Photoluminescence Efficiencies of Nanocrystalline versus Bulk Y2O3:Eu Phosphor—Revisited
Highly efficient yttrium oxide doped with trivalent europium (Y 2 O 3 :Eu) phosphor was prepared through precursors synthesized by hydrothermal method. Crystalline precursors, namely europium-doped yttrium carbonate (Y 2 (CO 3 ) 3 . 2H 2 O:Eu) and europium-doped yttrium hydroxy carbonate (Y(OH)CO 3 :Eu), were prepared by varying the concentration of yttrium to europium ions and urea in the reaction mixture. The precursor materials on annealing at 7001C gave nanocrystalline Y 2 O 3 :Eu, which was further processed at high temperatures in the absence and presence of sintering aid to yield phosphor materials with varying crystallite size and morphology. The precursors and phosphor material were characterized using FTIR, TGA, powder XRD, SEM, TEM, and photoluminescence (PL) spectral studies. The emission efficiency was found to depend on the crystallite size, morphology, and particle size of the phosphor materials. It was observed that phosphor material with spherical morphology and particle size of 0.5-1.0 lm with crystallite size of 100 nm has the highest PL efficiency.
Exploring Synthesis Techniques for Yttrium Based Phosphors
Defect and Diffusion Forum
In recent years, the term 'smart materials' which means the potential of a material having novel functional abilities, has become a buzz word. Luminescent materials held a lion's share amongst all functional materials. The research in these materials is nowadays becoming the frontline platform and has challenging options for the betterment of society. These materials have applications in diverse fields such as, radiation detection, monitoring and assessment, display devices (PDP, CRT, CTV, LCD, FPD, etc.), and Lighting devices (CFL, Hg Free lamps using VUV Xenon, Solid State lighting (SSL-LED blue chips, UV-LEDs, O-LEDs, etc.). The main and essential role is being played by the phosphors. The activity of the phosphor is also depending on the particle size and hence the nano-phase phosphor developments are very important aspect of development of functional materials. It is also very much clear now that the method of synthesis controls/decides a particle size of the final product. A particular method is better for a specific phosphor for getting the desired particle size of the final product. Scaling is also very much essential for instituting the specific method of synthesis for desired phosphor. These aspects are important for commercial production. Looking at the applications specified in first paragraph, one thing is common which is red correction required for display devices or lighting devices. The red correction in full-colour display/white light emission is essentially done by using Y 2 O 3 :Eu 3+ phosphor or Eu 3+ doped yttrium based hosts. Red emission is of Eu 3+ (5 D 0 7 F j , where j could be predominantly 2, 1, 3) when symmetrically organized environment. In this context, the review of yttrium based phosphors is being presented. This also covers our experience in synthesis of yttrium based luminescent materials with different methods of synthesis and their comparative aspects with regard to luminescence properties.